Advanced zwitterionic polymeric membranes for diverse applications beyond antifouling

Zwitterionic polymers, characterized by their possession of both cationic and anionic groups, are overall electrically neutral and capable of forming hydration layers on surfaces through hydrogen bonding and electrostatic interactions. In aqueous environments, these polymers stabilize water molecules with their hydrophilic headgroups, whereas their hydrophobic components assist in repelling oil molecules. Zwitterionic polymers dynamically adjust their charge distribution and intermolecular interactions in response to environmental changes such as pH and salinity variations, thereby maintaining their anti-fouling and oleophobic properties. Thus, modifying material surfaces with zwitterionic polymers is considered a particularly promising strategy for combating material fouling. This article focuses on the methods and mechanisms of membrane modification based on zwitterionic polymers, as well as their applications in anti-fouling and other domains. The focus of the discussion is on the modification techniques and mechanistic features of membranes based on zwitterionic polymers, including preformation surface modification and postformation surface enhancement. The topics under discussion include applications in oil–water separation, dye separation, seawater desalination, and antibiofouling. This important review also explores potential strategies and applications for addressing the unresolved challenges associated with zwitterionic polymer-modified membranes.